Crack growth-based fatigue life prediction using an equivalent initial flaw model. Part I: Uniaxial loading

A general methodology is proposed in this paper for fatigue life prediction using crack growth analysis. Part I of the paper focuses on the fatigue life prediction for smooth and notched specimens under uniaxial loading. Part II of the paper focuses on the fatigue life prediction under proportional and non-proportional multiaxial loading. The proposed methodology is based on a previously developed equivalent initial flaw size (EIFS) concept. The EIFS is determined by the Kitagawa-Takahashi diagram and does not require back-extrapolation calculation. Fatigue lives of smooth specimens can be predicted using crack growth analysis with the initial crack length equaling to the EIFS. An asymptotic interpolation method is used to estimate the stress intensity factor (SIF) solution for short and long cracks at notches and is used for fatigue life prediction of notched specimens. The well-known fatigue notch effect is discussed using the proposed EIFS methodology. Various experimental data of different metallic materials are used to validate the proposed methodology and reasonable agreement is observed between model predictions and experimental data.